Apparatus for the grinding of twist drills



Nov. 20, 1956 E. NDELIN 2,770,929

APPARATUS FOR THE GRINDING OF' TWIST DRILLS Filed July 9, 1954 2 Sheets-Sheet 1 /nven for:

Nov. 20, 1956 E. NDELIN 2,770,929

APPARATUS FOR THE GRINDING OF TWIST DRILLS Filed July 9, 1954 2 Sheets-Sheet 2 United States Patent 4C) APPARATUS FoR THE GRINDING oF TWIST nRILLs Eugen Ndelin, Ehingen, Wurttemberg, Germany assignor to Gottlieb Germany Application July 9, 1954, Serial No. 442,348 Claims priority, application Germany August 25, 1953 Claims. (Cl. 51219) Guhring, Ehingen, Wurttemberg,

various drill diameters, which previously was possible only for a certain inclination of the swivel pin, may now b e effected for two predetermined and preferred inclinations, i. e. for two point angles. v

Since with 95% of all drills a point angle of 116 or 118 is used and in addition with few exceptions only drills with a point angle of 130 are used, by the present invention a device is created with which on drills two point angles can be ground in like simple manner. In addition also other point angles can be ground.

Further according to the present .invention the device is so constructed that the swing axis for the rdrill support can b e changed Vfrom the inclined position for .the drills with a drill point angle of 116 or 118 in a simple manner to a second position, i. e., to an inclined position which corresponds to a point angle of preferably130". The change is brought about by simple tilting of the swing axis from -a limiting position to the other which corresponds to the second pointr angle. Furthermore,r in addition tothe adjusting devices of the drill support belonging to the rst inclined position of the swing axis, a second adjusting device with scales for dierent drill diameters for lthe second inclined `position of ythe-swing axis is provided so that :in both cases `by simple adjustment to values corresponding to the drill diameters in each case the precise distances X of the intersection of the swing axis with `the drill axis from the grinding disc can be adjusted. n

In order to lmake the apparatus suitable -for `the grinding of drills with rightf'hand-as well as withleft-hand twist, according to the present invention, two mountings lfor a bifurcated bearing member are provided on the tilting axis of the slide which carries. the swivel pin and is adjustable in a vertical direction relative to .the grinding wheel plane. For the purpose of varying the lip lclearanceangle the carrier for the drill support is adjustable transversely in relation to the bearing pivotableabout the swivel pin, and is-provided with corresponding -graduations The invention will now be described in more :detail in fconnection with a preferred embodiment given by way of example only, andwith reference tothe accompanying drawings in which: v

Fig. v1 isva side elevational eview, partly in section, of a `drill grinding apparatus according to the invention; j fFig. y2 is'a side elevational viewrof the swivel pinwith thefdrillsupport mounted on it;

ice

Fig. 3 is a diagrammatic view showing one position of` the swivel axis in relation to the grinding wheel;

Fig. 4 is a view similar to Fig. 3 but with the swivel axis in another position relative to the grinding wheel; Fig. 5 shows a device which is connected tothe slide for the adjustment of the point of intersection of :the swivel axis and the drill axis in relation to the grinding wheely for .the second position of inclination of the swivel pin, the upper structure ofthe device being omitted for the sake of clarity, and

Fig. 6A shows a device for the quick adjustment of the drill support.

In the apparatus shown in Fig. l a grinding wheel 3 is mounted on a shaft 2 `supported in the housing 1.`1 The housing of the apparatus carries a slide 4 slidably#` and lockably arranged in parallel relationship with the grinding wheel'. On the slide 4 are provided two out'- wardly extending bars 9 arranged'one behind the otherin parallel relationship, on which is slidably supported a cross slide 4. An upward extension 10 ofthe cross slidei 4' carries an axle 5, 5' extending parallel to the grindingwheel 3. Tiltably supported on one end of the axle y5l is aV bifurcated bearing member 6 `on which is secured' the swivel pin 7 for a holder 8. The holder S'comprises a transverse member 11 having a handle 12 for swivelling the drill support about the swivel pin 7. The transverse member 11 carries in a slotted guide 13, 13a, a carrier 14 adjustable parallel to the grinding wheel by means of a set screw'14a, and comprising a grooved block'lS.,

adapted to support the front end of the drill. In the supporting member A15r is mounted a gauging pin I15a heldy in adjusted position by yset screw 15b which in case`of being accidentally damaged by the grinding wheel may,

be easily replaced, and with the help of which the drill support can be exactly adjusted in relation to Vthe grinding wheel by means of the adjustable cross slide Afin. the basic position, i. e. when the swivel pin 7 is inclined towards the grinding wheel at an angle of 116. In .the transverse member 11 is further provided a longitudinal slot 16 in which a slider 13 is arranged for slidingmovel ment. n A pin 17 of this slider constitutes a guide for a carrier 19 which is adjustable perpendicular to the transverse member. A `spindle provided for effecting fsuch.

adjustment is designated 19a. In its lower portion the carrier 19 comprises a centering spindle 20 having a conical front portion adapted to receive the end ofthe drill.

For the adjustment of the drill support comprising the two carriers 14 and 19, in relation to the point of inter# section of the drill axis and the axis of swivel pin 7, so that the distance X from the point of intersection to the surface of the grinding wheel agrees with the drill size, the carriers 14 and 19 are provided with graduated .scales 14b, 19h, which can be adjusted `relative to iixed marks provided on the transverse member 11 and the slider 18, respectively. For a drill of given diameter both scales are set to the same number which indicate thediame'ter of the drill. In order to keep the cutting edgesV of the drill in a vertical position during grinding, the transverse.,

member 11 is rprovided with .a device whichv securely lo?4 cates the drill in rthis position. For this purposea doublearmed lever 22 is rotatably arranged on a pivot 21, an

.the

indexing wheel 23 being rotatably supported on shorter `arm of this double-armed lever. -the indexing wheel 23 is provided with pins y2410i lvarious diameters which are adapted to engage the spiral flutes of the drill and are retained therein by spring (not shown). edge, the indexing pin is retracted from the spiral tinte by depressing the longer arm of the double-'armedl lever 22,.;and pressed into Vthe other spiral flute after the"drill has 'been rotated through 180.

Patented Nov. 20,` 1956 On its periphery` theaction of For grinding the second .cutting If it is desired to change the lip clearance angle, the drill may be given an unsymmetrical position within the grinding cone. For this purpose the arm 8 is adjustable on its hub portion 8a longitudinally of a guide 25 extending in the swivelling direction, the end positions being limited by set screws 26.

Marks (not shown) provided on the arm 8 and on' the hub portion 8a permit an exact setting of the lip clearance angle.

The apparatus is suitable notonly for the grinding of right-hand twist drills, but also of left-hand twist drills. Wheny it is desired to grind left-hand twist drills, the swivel pin supported on the tilting axle 5, is set onto the latter on end 5 on the other side of the cross slide 4', the Adirection of rotation of the grinding wheel is changed, and the drill support is re-adjusted by moving the arm 8 longitudinally of the guide 25, until a mark provided on the arm S registers with a mark for left-hand twist drills proivded on the hub portion 8a. In this grinding the drill point because of the generation of a certain rear grinding angle and because the grinding grains attack the grinding disc, a certain position laterally of the vertical median plane of the grinding disc is necessary. In order, then, to obtain the same elect for left-hand drills, i. e., with grooves extending counter-clockwise, axle 7 with the entire device situated thereon is placed on the right-hand bearing bolt 5 (Figure 5) and clamped there suitably. In doing so also the rotation direction of the grinding disc is reversed. Only in this manner is it possible to obtain also for left-hand drills the same grinding conditions as prevail With right-hand drills. A

The bearing member 6 for the swivel pin 7, which rests on the tilting axle 5, is bifurcated and comprises two legs 2829.` The lower end faces 30, resp. 31 of the fork legs are inclined at certain angles to the fork axis, so that upon tilting of the swivel pin the abutment of these faces against a common plane surface 32 determines the inclination of the swivel pin 7 in two positions.l 1

In the position shown in Figs. 1, 2 and 3, adjustment ofthe apparatus to various drill diameters may be effected by adjusting the drill support in the manner previously described.

If it is desired to grind drills with a point angle corresponding `to the second inclined position of the swivel pin 7, the latter together with the drill support must rst be slid back a certain distance on the support bars 9, so that it may be tilted in a direction towards the grindingwheel until the end face 30 of the fork leg 28 abuts against the plane surface 32. In order to assure that after` this tilting the point of intersection of drill and swivel` pin 7 has the correct distance X from the grinding wheel, which corresponds tothe drills to `be` ground, the travel of the slide 4' is limited by an adjusting device 33, against which the slide 4' abuts.

Fig. 5 shows the slide withthe adjusting device 33. The slide 4 which is slidably supported on the support bars 9, comprises an upwardly directed extension 10. Mounted in this extension and` projecting therefrom on both sides is the axle 5. By this arrangement it is possible, as previously described, to place the bifurcated bearing member 6 with the drill support on the axle 5 either on the left side, as shown in the drawing, or on the right side of extension 10 in order to permit grinding of right-hand and left-hand twist drills, and to clamp it in position by means of the nuts 34 and 35, respectively. Thereby, one of the two end faces 30, resp. 31 of the bifurcated bearing member 6 will abut against the-plane surface 32 of the slide. j .j

The slide is further provided with a bore 36, The two supporting bars for the slide 4 are connected at their outwardly directed ends by a-bridge piece 37. In this bridge piece is supported a screw spindle 38 comprising a hand wheel 39 by meansof which the slide 4 is adjustable longitudinally of its supporting bars 9. Between the slide 4 and the bridge piece 37 isarrauged e QIQSS` member 40 which is also slidable on the bars 9 and is adapted to be clamped thereon by means of screws 41. The cross member 40 comprises a bar 42 projecting towards the slide 4 and freely movable in the bore 36 thereof. On this bar are provided three marks 43 having the form of notches or the like, the purpose of which is to be described in the following.. Moreover, the cross member 40 on its upper part comprises a diagonal guide 44 having a graduation 45. Opposite this ixed diagonal guide a ilat slider 46 is mounted on the cross member 40, said slider 46 being adjustable by means of the slot 47 and adapted to be locked in position by means of a screw 48.

Fig. 6 shows a device for the quick adjustment of the parts constituting the drill support, in which the drill carriers are not adjusted in their height by means of screws, but are freely slidable and adapted to be supported and locked at various heights. For this purpose a supporting pin 50 is mounted on the transverse memberll,

and the adjustable carrier 14 supporting the front drill support 15 carries on an upwardly extending angular arm 51 a spiral shaped disk 53 which is rotatable about an axle 52 and on its periphery is provided with notches 54 adapted to receive the point of the supporting pin 50. The carrier 14 can be released and locked in position by means of a wing nut 55. This wing nut 55 has a left-hand thread, its wing extending upwardly in the locked position, so that release is effected by turning the nut towards the right, as seen in the drawing. By this arrangement contact of the wing with the grinding wheel rotating in the opposite direction is avoided when loosening the nut. For the purpose of adjusting the front drill support to a given type of drill, the wing nut 55 is loosened by rotating it in the corresponding direction, the carrier 14 is displaced in its slotted guide, and the disc 53 is rotated until it is possible to bring the notch corresponding to the drill to be ground into engagement with the point of the pin 50, whereupon the carrier 14 is locked in position by tightening the wing nut 55.

Adjustment of the rear carrier 19 is effected in a similar manner. The carrier 19 is supported for adjustment perpendicular to the transverse member 11 by means of a slotted guide in a block 56 mounted for sliding movement in the longitudinal slot 16 of the transverse member 11.

The block 56 has likewise secured thereto a supporting pin 57. On its upper end, the carrier 19 is also provided with a spiral-shaped disc 59 which is rotatable about an axle 58 and on its periphery is provided with notches 54. The carrier 19 is adapted to be released and locked in position by means of a wing nut 60 arranged on the rear side of the transverse member 11, i. e. on the side opposite the wing nut 55, so that adjustment is effected in a manner exactly similar to that described in the foregoing. The rotatable spiral-shaped discs comprise as many notches as are necessary for the drills of various diameters of one drill series, for example for drills ranging from l0 to 20 millimeters in diameter. In practice it is suticient to provide notches corresponding to a graduation by V2 of a millimeter. Under the head of each of the pivot screws 52 and 58 for the discs 53, 59 is provided a thin Belleville washer, so that the discs are held in any desired position by frictional engagement, but may easily be adjusted to different positions.

When adjustment is effected by means of the spiral- `shaped discs, the aforementioned adjustment scales may be according to the invention. The drill diameters are, hown ever, subdivided into several drill series, for example three. The first group comprises, for example, drills from 0.5 to 3 millimeters, the second group drills from 3 to 10 millimeters, and the third group drills from to 2O millimeters. Special drill supports are attached to the grindingapparatus for each group of drills.

For grinding the drills the device is first set to a basic adjustment. This is brought about by adjusting the entire device part lying in front of the grinding face with the drill support at the position of swing axis 7 which corresponds to vthe mostly used drill point angle (U6-118), inclined tothe grinding face of the grinding disc. For this purpose serves setting pin a at the front drill support 15 which is once so set by means of screw 15b on the drill support 15 that for any drill a correct distance X of the intersection of the drill axis with the swing axis 7 from the grinding yface results, if the point of the setting pin 15a is at a certain very slight distance from the grinding face of the grinding disc. After this basic setting for all `drills of different diameters the precise grind results without other steps, if the two parts 14, 19 of the drill support are set to the same numbers corresponding to the respective drill. For grinding the inserted drill the drill support 14, 19 is swung by means of handle 12 about swing axis 7 to and fro and the drill, as needed, additionally adjusted by means of spindle 20 toward the grinding disc. For varying the rear grind of the drill point the drill support 14, 19 can be adjusted by means of guide 25 andset screw 26 laterally.

In caseiof wear and deviation of the grinding disc it is only necessary to again adjust the part with the drill support toward the grinding face to such an extent that the point of the setting pin receives again the above-mentioned definite vslight spacing from the grinding face.

In this manner drills of different diameter can be ground precisely to the same point angle.

If drills of different diameters are to be ground to another point angle conditioned by the second inclined position of the swing axis 7, the above-mentioned basic setting of the device remains the same, but a change of the grinding device from this basic setting is eiected in the following manner:

In the normal position shown in Figs. 1 and 2 of the device, the carrier 40 is rst rendered movable by loosening screws 41. Then the carrier is pushed against the support 4 until one of the three notches indicating a certain drill group, and located on the measuring pin 36, is exactly aligned with the rear edge of the support. This displacement constitutes the basic setting for the respective drill group to be ground for which a special drill support is placed on the device.

After this basic adjustment for a drill group the carrier 40 is clamped by screws 41 on the guide rods 9. Scale 45 on inclined face 44 indicates the several drill diameters. Thus it is only necessary in placing a certain drill to so set the slide 46 that its mark is set to the number of scale 45 corresponding to the Vdrill diameter. Thereupon, by means of vhand wheel 39 and spindle 38, the support 4 is turned back far enough so that its rear edge abuts against slide 46. Now the swing axle with the drill support is tilted toward the grinding disc and the forked support 6 is clamped by nut 34 or 35, respectively, depending on whether the drill support for grinding right-hand or lefthand drills is located on the support 4 to the left or to the right. Owing to this setting the above-mentioned intersection has for each drill precisely the distance X from the grinding disc so that a satisfactory grind is obtained. The setting pin located at the front drill support in this setting is no longer needed but, as stated above, serves only for setting the device to the basic setting.

Also in the second position of the swing axle 7 the grinding of the drill is brought about by swinging the drill support to and fro about swing axis 7, the rear grind on the drill point being possible also in this case by lateral v6 displacement of the drill support and set screw 26.

I claim:

l. Apparatus for the grinding of twist drills comprising a housing, a grinding disc rotatably supported on a horizontal shaft extending from said housing, a rst slide mounted on said housing and adjustable in a vertical direction parallel to the grinding disc plane, two supporting bars extending horizontally and outwardly from said first slide in parallel relationship, a second slide slidably mounted on said supporting bars, an axle mounted on said second slide and extending parallel to the grinding ywheel plane, a bifurcated bearing member mounted for tilting movement about said axle, a swivel pin mounted on said bearing member and inclined towards the grinding wheel, a drill support pivotally mounted on said swivel pin, and adjusting means mounted on said supporting bars and permitting adjustment of the point of intersection of the swivel axis and the drill axis in relation to the grinding disc plane for certain groups of drills and various drill diameters.

2. Apparatus for the grinding of twist-drills comprising a housing, a grinding disc rotatably supported on a horizontal shaft extending from said housing, a `first slide mounted on said housing and adjustable in a vertical direction parallel to the grinding disc plane, two supporting bars extending horizontally and outwardly from said first slide in parallel relationship, a second slide slidably mounted on said supporting bars, an axle mounted on said second slide and extending parallel to the grinding disc plane,^a bifurcated bearing member mounted for tilting movement about said axle, a swivel pin mounted on said bearing member and inclined towards the grinding disc, a drill support pivotally mounted on said swivel pin, and adjusting means mounted on said supporting bars and permitting adjustment of the point of intersection of the swivel axis and the drill axis in relation to the grinding disc plane for certain groups of drills and various drill diameters, said adjusting means comprising a stop member mounted for sliding movement on said supporting bars and adapted to be adjusted thereon at certain distances from the grinding disc plane corresponding to the group and the diameter of drills to be ground and constituting an abutment for said second slide, the position of said stop member on said supporting bars determining the position of the point of intersection of the swivel axis and the drill axis relative to the grinding disc plane for that position of inclination of the swivel pin, that corresponds to the greaterdrill point angle.

3. In apparatus as set forth in claim 2, said adjusting means comprising a slidable member, a measuring piu projecting from said transverse member towards said second slide and provided with indicia or the like, a diagonal guide provided on said member, a slider adjustable longitudinally of said diagonal guide and in a direction towards said second slide .and constituting an abutment for the latter.

4. A device for sharpening twist drills, comprising a grinding disc mounted for rotation on a horizontal shaft and presenting a plane surface for grinding drill bits, a horizontal table mounted below said disc and adjustable parallel to the axis of said disc, an integral block on said table located in the vertical plane of the axis of said disc, an axle having ends extending from said block and to each side thereof parallel to the face of said disc, a swivel pin for selective mounting on said axle ends, a mounting for said swivel pin including two legs to be placed astride of said axle to one side of said block, the

by means of guide 25 lower ends of said legs forming stops to selectively bear' against said table to determine two diierent desired inclinations of said swivel pin toward said disc, and a drill holding clamp swingably mounted on said swivel pin.

5. In apparatus as set forth in claim 4, and having a drill support pivotable about said swivel pin, said drill support comprising a member, two slidable drill carriers'.

mounted thereon, espiral-shaped disc rotatably mounted on each of said carriers, and a fixed supporting member secured to said member near each of said discs and adapted to supportingly engage the peripheral edge of said spiral-shaped disc, the radial distance of given points on the periphery of said discs determining the position of said carriers relative to said member.

6. In apparatus as set forth in claim 5, spiral shaped discs rotatably mounted on the upper portions of said slidable drill carriers, notches provided in the periphery of said spiral shaped discs, Xed supporting pins secured to said memberand.adapted to engage into said notches, and clamping screws provided for clamping said drill carriers to said member, whereby adjustment of said drill carriers is etected by loosening said clamping screws, rotating said discs, engaging said supporting pins in one of said notches corresponding to the drill to be ground, and nally tightening said clamping screws.

7. The device of claim 4, in which an adjustment stop is provided for said horizontal table, said stop comprising a primary element that can be clamped in the path of adjustment of said table, means to indicate a preliminary setting of said primary element and a secondary element carrying the stop surface mounted on said primary element and adapted to be `accurately adjusted with regard to said primary element as required in grinding drills of different diameters.

8. The device of claim 7, in which said secondary element comprises a wedge-shaped abutment element slidable on said primary element against a guide set at an angle to the direction of adjustment so that a at side of said wedge-shaped abutment element will be presented as a stop for said table.

9. The device of claim 4, in which said drill holding clamp comprises a member, a carrier mounted for generally vertical adjustment on each end portion of said element, means to clamp said carriers in adjusted position, a stop pin mounted on said member adjacent each said carrier, and an adjustment stop mounted on each said carrier, said stops each comprising a pivoted plate element lying in the plane of said member and having a spiral and notched edge configuration such that each notch along said spiral edge, when brought into engagement with said stop pin adjacent said carrier, will position said carrier to correctly position a drill of a size corresponding to said notch.

l0. In a device of the class described a grinding disc, a swivel pin lying in a plane normal to said disc, a drill holder comprising a member rotatably mounted on and lying at an angle to said swivel pin, a iirst carrier mounted on said member adjustable in a direction parallel to the face of said grinding disc in the plane of said swivel pin, said carrier comprising a grooved block for receiving the front end of a drill to be ground, a second carrier which is adjustable in a direction normal to the length of said member and comprising a centering spindle on its lower end to receive the rear end of a drill to be ground, and indicia on said member and on said irst and second carriers by which said carriers may be pre-set to receive and accurately align a drill to be ground.

References Cited in the tile of this patent UNITED STATES PATENTS i 497,095 Hall May 9, 1893 1,391,034 Williams Sept. 20, 1921 2,139,938 Dixon Dec. 13, 1938 2,486,335 Smith et al Oct. 25, 1949 FOREIGN PATENTS 965,918 France Feb. 22, 1950 

